Human Microbiome Project will map the genetic sequences of bacterial world hidden in our bodies!

If you recall the biology course in the college, the average human being is a collection of about 10 trillion eukaryotic cells – each with a nucleus storing 23 chromosome pairs of nucleic DNA, and a collection of membrane-bound organelles including mitochondria with genetic material of their own. What is less obviously that each of us is also carrying around 100 trillion prokaryotic cells, from thousands of different bacteria species.

Following up on the Human Genome Project – which aimed to decode the three billion nucleotides in the human genome – the Human Microbiome Project seeks to identify and annotate the genetic sequences of those bacteria.

Many of those bacteria play critical roles in biological processes that sustain human life – digestion is just one of them. Others may be the benign residents of niches where more harmful microorganisms might otherwise live. Already, it has been theorized that these bacteria has an impact on diseases including diabetes, autism, cancer, and cardiovascular diseases.

The initial estimates are that collectively these bacterial species are thought to have 100 times more genetic material than the colony of human cells. Well, this is expected to be so, since the variety of distinct organism is expected to be huge…

Some initial DNA sequencing projects sequencing DNA from the human gut – have found that there are thousands of species, and that the bacterial micro-environments are dramatically different in different areas of our bodies – the mouth has its own microbial environment (microbiome), for example, which is very different from the skin. On the other hand there are big similarities between people – if you look at the bacteria living in the gut of two different people, they have a lot in common. It might turn out that many of these bacteria are “inherited” or transferred as “Lamarck’s dogma” have been postulated long time ago – that they are passed on from parents at some point during childhood, or maybe even acquired from others in our community.

The Human Microbiome Project is one of the several metagenomics efforts following the most popular to the public one – Craig Venter’s Global Ocean Sampling Expedition. The project outcomes might serve both the practical function of helping to better understand and treat human disease and the more esoteric one of refining our understanding of what it means to be a human being, biochemically at least.

Currently, researchers can grow only some of the bacteria, fungi and viruses in a laboratory setting. However, new genomic techniques can identify minute amounts of microbial DNA in an individual and determine its identity by comparing the genetic signature to known sequences in the project’s data base.

The Human Microbiome Project reference collection consists of 178 microbial genomes of total approximately 900 microbial genomes of bacteria, viruses and fungi. These data will then be used by the researchers to characterize the microbial communities found in samples taken from healthy human volunteers and, later, those with specific illnesses. Samples are currently being collected for Human Microbiome Project from five areas of the body:

  • the digestive tract
  • the mouth
  • the skin
  • the nose
  • the vagina

Although that the Human Microbiome Project have been initiated in 2008, it still did not provide any valuable insights (or at least to my knowledge!). There were some published comparative analysis (they have identified 29,693 previously undiscovered, proteins in the reference collection and compared their results to the available sequenced microbial genomes and found 14,064 novel proteins). Probably the reason is that just the sequencing of the Human Microbiome is just the first step, the more important part is to identify the structural and functional elements within the sequences and to annotate them.